1. Field of the Invention
The present invention relates to an electrode binder for a secondary battery having improved bonding force, an anode for a secondary battery including the same, and a lithium secondary battery including the anode.
2. Description of the Related Art
Recently, in line with the realization of miniaturization and weight reduction in electronic devices and the generalization of the use of portable electronic devices, research into lithium secondary batteries used as power sources of such electronic devices has been actively conducted.
In general, a lithium secondary battery includes an anode using a copper current collector, a cathode using an aluminum current collector, and a separator disposed therebetween.
Resistance may increase and the performance of a battery may be deteriorated while an electrode active material is exfoliated from an electrode current collector due to volume changes in the anode and cathode during repetitive charge and discharge of the secondary battery. In particular, such an exfoliation phenomenon may more frequently occur in the anode, in which the deformation of an active material layer due to expansion and shrinkage is large, than in the cathode.
Typically, a polymer binder, such as polyvinylidene fluoride (PVdF), has been used for improving binding force between electrode active material particles or between the electrode active material particles and a current collector. The binding force between a separator formed of a material similar to the binder and an electrode active material layer may increase during the charge and discharge are repeated, but the binding force between an electrode current collector formed of a material different from the binder and an electrode active material layer may still be low. When the amount of the binder is increased to prevent this, the amount of the electrode active material may not only be relatively decreased, but electrical resistance of an electrode may also be increased due to electrical insulation. Thus, capacity of the battery may be reduced.
Therefore, the development of a binder for a secondary battery, which may secure adhesion between the electrode active material and the electrode current collector and may simultaneously prevent the reduction of the performance of the battery, is urgently needed.